# Merge Sorting:

​

def merge(a,b):

    merged_list = []

    len_a,len_b = len(a),len(b)

    index_a,index_b = 0,0

​

    while index_a < len_a and index_b < len_b:

        if a[index_a] < b[index_b]:

            merged_list.append(a[index_a])

            index_a += 1

        else:

            merged_list.append(b[index_b])

            index_b += 1

​

    if index_a < len_a:

        merged_list.extend(a[index_a:])

    elif index_b < len_b:

        merged_list.extend(b[index_b:])

    return merged_list

​

# Now merge sorting:

def merge_sort(L):

    if len(L) <= 1:

        return L

    mid = len(L)//2

    left = merge_sort(L[:mid])

    right = merge_sort(L[mid:])

    return merge(left,right)

​

# input list:

L = [[4,7,2,3],[10],[10,9,8,7,6],[2,3,1],[1,2],[2,1]]

total_sorted_list = []

for i in L:

    sorted_list = merge_sort(i)

    print("Original List:",i)

    print("Sorted List:",sorted_list)

    print()

​

# Output:

Original List: [4, 7, 2, 3]

Sorted List: [2, 3, 4, 7]

​

Original List: [10]

Sorted List: [10]

​

Original List: [10, 9, 8, 7, 6]

Sorted List: [6, 7, 8, 9, 10]

​

Original List: [2, 3, 1]

Sorted List: [1, 2, 3]

​

Original List: [1, 2]

Sorted List: [1, 2]

​

Original List: [2, 1]

Sorted List: [1, 2]

def merge_sort(arr):

    if len(arr) <= 1:

        return arr

​

    mid = len(arr) // 2

    left = merge_sort(arr[:mid])

    right = merge_sort(arr[mid:])

​

    return merge(left, right)

​

def merge(left, right):

    result = []

    i = j = 0

​

    while i < len(left) and j < len(right):

        if left[i] < right[j]:

            result.append(left[i])

            i += 1

        else:

            result.append(right[j])

            j += 1

​

    result.extend(left[i:])

    result.extend(right[j:])

    return result

​

arr = [38, 27, 43, 3, 9, 82, 10]

sorted_arr = merge_sort(arr)

print(sorted_arr)  # Output: [3, 9, 10, 27, 38, 43, 82]

def mergeSort(A):

    if len(A) > 1:

        print('Splitting' , A)

        mid = len(A)//2

        left = A[:mid]

        right = A[mid:]

        mergeSort(left)

        mergeSort(right)

        i = j = k = 0

        while i < len(left) and j < len(right):

            if left[i] < right[j]:

                A[k] = left[i]

                i = i+1

            else:

                A[k] = left[i]

                j = j+1

            k = k+1

        while i < len(left):

            A[k] = left[i]

            i = i+1

            k = k+1

        while j < len(right):

            A[k] = right[j]

            j = j+1

            k = k+1

        print('merging' , A)

        return(A)

def mergeSort(arr):

    if len(arr) > 1:

         # Finding the mid of the array

        mid = len(arr)//2

        # Dividing the array elements

        L = arr[:mid]

        # into 2 halves

        R = arr[mid:]

        # Sorting the first half

        mergeSort(L)

        # Sorting the second half

        mergeSort(R)

        i = j = k = 0

        # Copy data to temp arrays L[] and R[]

        while i < len(L) and j < len(R):

            if L[i] <= R[j]:

                arr[k] = L[i]

                i += 1

            else:

                arr[k] = R[j]

                j += 1

            k += 1

        # Checking if any element was left

        while i < len(L):

            arr[k] = L[i]

            i += 1

            k += 1

        while j < len(R):

            arr[k] = R[j]

            j += 1

            k += 1

# Code to print the list

def printList(arr):

    for i in range(len(arr)):

        print(arr[i], end=" ")

    print()

# Driver Code

if __name__ == '__main__':

    arr = [12, 11, 13, 5, 6, 7]

    print("Given array is", end="\n")

    printList(arr)

    mergeSort(arr)

    print("Sorted array is: ", end="\n")

    printList(arr)

# This code is contributed by Mayank Khanna

# Python program for implementation of MergeSort

def mergeSort(arr):

    if len(arr) > 1:

         # Finding the mid of the array

        mid = len(arr)//2

        # Dividing the array elements

        L = arr[:mid]

        # into 2 halves

        R = arr[mid:]

        # Sorting the first half

        mergeSort(L)

        # Sorting the second half

        mergeSort(R)

        i = j = k = 0

        # Copy data to temp arrays L[] and R[]

        while i < len(L) and j < len(R):

            if L[i] < R[j]:

                arr[k] = L[i]

                i += 1

            else:

                arr[k] = R[j]

                j += 1

            k += 1

        # Checking if any element was left

        while i < len(L):

            arr[k] = L[i]

            i += 1

            k += 1

        while j < len(R):

            arr[k] = R[j]

            j += 1

            k += 1

# Code to print the list

def printList(arr):

    for i in range(len(arr)):

        print(arr[i], end=" ")

    print()

# Driver Code

if __name__ == '__main__':

    arr = [12, 11, 13, 5, 6, 7]

    print("Given array is", end="\n")

    printList(arr)

    mergeSort(arr)

    print("Sorted array is: ", end="\n")

    printList(arr)

# This code is contributed by Mayank Khanna

ev = [12,42,53,14,86,34]

​

def Division(ev):

    i = 0

    j = 0

    k = 0

    if len(ev) > 1:

        middle = (0 + (len(ev)//2))

        l = ev[0:middle]

        r = ev[middle:]

        Division(l)

        Division(r)

​

        while (i < len(l) and j < len(r)):

            if l[i] <= r[j]:

                ev[k] = l[i]

                i = i + 1

                k = k + 1

            else:

                ev[k] = r[j]

                j = j + 1

                k = k + 1

        while i < len(l):

               ev[k] = l[i]

               i = i + 1

               k = k + 1

​

        while j < len(r):

               ev[k] = r[j]

               j = j + 1

               k = k + 1

​

def printList(ev):

    for x in range(len(ev)):

        print(ev[x],end=" ")

    print()

​

# Driver Code

print("Before:",end=" ")

printList(ev)

Division(ev)

print()

print("After:",end=" ")

printList(ev)

​

​

​

​

​

​

def sortList(left, right):

    sortedList = []

    j = 0

    i = 0

    while i < len(left) and j < len(right):

        if left[i] < right[j]:

            sortedList.append(left[i])

            i += 1

        else:

            sortedList.append(right[j])

            j += 1

    if i < len(left):

        sortedList.extend(left[i:])

    elif j < len(right):

        sortedList.extend(right[j:])

    return sortedList

​

​

def mergeSort(A):

    if len(A) == 0:

        return None

    if len(A) == 1:

        return A

    mid = len(A) // 2

    left = mergeSort(A[0:mid])

    right = mergeSort(A[mid:])

    sortedList = sortList(left, right)

    return sortedList

# Python program for implementation of MergeSort

# Merges two subarrays of arr[].

# First subarray is arr[l..m]

# Second subarray is arr[m+1..r]

def merge(arr, l, m, r):

    n1 = m - l + 1

    n2 = r - m

    # create temp arrays

    L = [0] * (n1)

    R = [0] * (n2)

    # Copy data to temp arrays L[] and R[]

    for i in range(0, n1):

        L[i] = arr[l + i]

    for j in range(0, n2):

        R[j] = arr[m + 1 + j]

    # Merge the temp arrays back into arr[l..r]

    i = 0     # Initial index of first subarray

    j = 0     # Initial index of second subarray

    k = l     # Initial index of merged subarray

    while i < n1 and j < n2:

        if L[i] <= R[j]:

            arr[k] = L[i]

            i += 1

        else:

            arr[k] = R[j]

            j += 1

        k += 1

    # Copy the remaining elements of L[], if there

    # are any

    while i < n1:

        arr[k] = L[i]

        i += 1

        k += 1

    # Copy the remaining elements of R[], if there

    # are any

    while j < n2:

        arr[k] = R[j]

        j += 1

        k += 1

# l is for left index and r is right index of the

# sub-array of arr to be sorted

def mergeSort(arr, l, r):

    if l < r:

        # Same as (l+r)//2, but avoids overflow for

        # large l and h

        m = l+(r-l)//2

        # Sort first and second halves

        mergeSort(arr, l, m)

        mergeSort(arr, m+1, r)

        merge(arr, l, m, r)

# Driver code to test above

arr = [12, 11, 13, 5, 6, 7]

n = len(arr)

print("Given array is")

for i in range(n):

    print("%d" % arr[i],end=" ")

mergeSort(arr, 0, n-1)

print("\n\nSorted array is")

for i in range(n):

    print("%d" % arr[i],end=" ")

# This code is contributed by Mohit Kumra

# Python program for implementation of MergeSort

# Merges two subarrays of arr[].

# First subarray is arr[l..m]

# Second subarray is arr[m+1..r]

def merge(arr, l, m, r):

    n1 = m - l + 1

    n2 = r - m

    # create temp arrays

    L = [0] * (n1)

    R = [0] * (n2)

    # Copy data to temp arrays L[] and R[]

    for i in range(0, n1):

        L[i] = arr[l + i]

    for j in range(0, n2):

        R[j] = arr[m + 1 + j]

    # Merge the temp arrays back into arr[l..r]

    i = 0     # Initial index of first subarray

    j = 0     # Initial index of second subarray

    k = l     # Initial index of merged subarray

    while i < n1 and j < n2:

        if L[i] <= R[j]:

            arr[k] = L[i]

            i += 1

        else:

            arr[k] = R[j]

            j += 1

        k += 1

    # Copy the remaining elements of L[], if there

    # are any

    while i < n1:

        arr[k] = L[i]

        i += 1

        k += 1

    # Copy the remaining elements of R[], if there

    # are any

    while j < n2:

        arr[k] = R[j]

        j += 1

        k += 1

# l is for left index and r is right index of the

# sub-array of arr to be sorted

def mergeSort(arr, l, r):

    if l < r:

        # Same as (l+r)//2, but avoids overflow for

        # large l and h

        m = l+(r-l)//2

        # Sort first and second halves

        mergeSort(arr, l, m)

        mergeSort(arr, m+1, r)

        merge(arr, l, m, r)

# Driver code to test above

arr = [12, 11, 13, 5, 6, 7]

n = len(arr)

print("Given array is")

for i in range(n):

    print("%d" % arr[i],end=" ")

mergeSort(arr, 0, n-1)

print("\n\nSorted array is")

for i in range(n):

    print("%d" % arr[i],end=" ")